Add Function to Ensure Dialect is Imported

[ktogo]

Is your feature request related to a problem? Please describe.

Goqu generates queries with unintended default dialect when forget to import the dialect in every files.

This situation especially occurs when running single unit test.

---

Describe the solution you'd like

Provide following functions which requires specific dialect to be imported.

package goqu

// RequireDialect returns dialect if available, otherwise returns an error.
func RequireDialect(dialect string) (DialectWrapper, error)

// MustDialect returns dialect if available, otherwise panics.
func MustDialect(dialect string) DialectWrapper

---

Describe alternatives you've considered

The following code achieves it (by non-straightforward way though), but I would like to suggest this to be a part of goqu official functions.

func RequireDialect(dialect string) (goqu.DialectWrapper, error) {
	d := goqu.Dialect(dialect)
	if goqu.GetDialect(dialect).Dialect() == dialect {
		return d, nil
	}
	return d, errors.New("goqu dialect unavailable: " + dialect)
}

func MustDialect(dialect string) goqu.DialectWrapper {
	d, err := RequireDialect(dialect)
	if err != nil {
		panic(err)
	}
	return d
}

---

Dialect

• postgres
• mysql
• sqlite3

Additional context
Add any other context or screenshots about the feature request here.

[ktogo]

Or another approach:

package goqu

// RequireDialect returns an error if specified dialect is unavailable.
func RequireDialect(dialect string) (error)

Usage:

if err := goqu.RequireDialect("postgres"); err != nil {
	panic(err)
}

goqu.Dialect("postgres").Select("*") //...